The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Advancements in lighting technologies have led to more efficient lighting devices. In general, the efficiency of a lighting device can be defined by the amount of visible light output (lumens) per input power unit (watt).
For example, traditional incandescent light bulbs are generally very inefficient in producing lights, within the range of 10-17 lumens per watt. In other words, they are only able to convert five percent of input power into visible light, with the remaining power being converted into heat.
Due to the inefficiencies of the incandescent light bulbs, they have been slowly replaced by newer lighting technologies such as compact fluorescent lamps (CFL). Compared to incandescent light bulbs, CFLs are a lot more efficient in product visible light, generally rating at between 50-70 lumens per watt. In other words, CFLs are capable of converting 9-11% of input power into visible light. Even though CFLs are superior to the traditional incandescent light bulbs in terms of efficiency, they are far from optimal.
Light-emitting diodes (LEDs) have been developed and improved over the recent years to a point that they can replace incandescent lights and CFLs. The apparent advantage of LEDs is that they are much more efficient in producing visible lights than the older technologies. Numerous iterations of LEDs have been developed over the years and the latest iteration can achieve a luminous efficacy of over 90 lumens per watt.
As one can see, even though newer lighting devices with higher efficiency have been developed over the years, the process of development has been slow, and the efficiency improvement over previous technologies has not been great. In addition, a phase-out period is required each time a new lighting device is introduced to the market when consumers have to completely use up their supply of old light bulbs before they will replace them with the newer devices.
Efforts have been made to improve on existing lighting technologies without introducing new devices to the market. For example, U.S. patent publication 2012/0146534 to Yu et al., filed Jun. 14, 2012, entitled “DC/AC Inverter” discloses an efficient system for operating a fluorescent lamp by driving a circuit at around the resonant frequency according to the conduction state of the fluorescent lamp. U.S. Pat. No. 4,023,067 to Zelina et al., issued May 10, 1977, entitled “Inverter Ballast Circuit” and U.S. Pat. No. 4,973,885 to Kerwin, issued Nov. 27, 1990, entitled “Low Voltage Direct Current (DC) Powered Fluorescent Lamp” suggest that operating a fluorescent lamp at a high frequency improves the efficiency. However, only frequencies of up to 10 kHz have been experimented and only up to a luminous efficacy of 110 lumens per watt have been achieved, as disclosed in the article by J. D. Hooker entitled “Effect of Operating Frequency” which can be found at the website http://www.lamptech.co.uk/Documents/FL%20Frequency.htm.
In addition, in an attempt to improve lighting efficiency using existing large fluorescent lamp ballasts, International Patent Publication WO2012/068687 to Joset et al. filed Nov. 23, 2011, entitled “LED Lamp with Variable Input Power Supply” discloses a light emitting diode lighting device that can be used with common fluorescent fixtures (e.g., ballasts) without the need for a retrofit.
Other efforts have also been made to improve efficiency of LED lighting devices. For example, U.S. Pat. No. 8,288,924 to Ibbetson issued Oct. 16, 2012, entitled “High Efficacy White LED” discloses manipulating the current levels of the LED circuit to improve the efficiency of the LED lamps.
However, using existing technologies to drive fluorescent lamps or LED lamps still produce a large amount of heat due to inefficiency of the system. As such, there is still a need to improve on existing lighting circuits to provide more efficient lighting systems.
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.